Tag: chemistry

Questions Related to chemistry

$3C _2H _2\rightleftharpoons C _6H _6$ 


The above reaction is performed in a 1-liter vessel. Equilibrium is established when $0.5\ mole$ of benzene is present at a certain temperature. If the equilibrium constant is $4\ L^2mol^{-2}$. The total number of mole of the substance present at equilibrium is:

chemistry chemical equilibrium equilibrium in chemical processes introduction to equilibrium chemical equilibrium and acids-bases

  1. $0.5$

  2. $1$

  3. $1.5$

  4. $2$

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Correct Option: A

In $ A _{3}(g) \leftrightharpoons3A(g) $ reaction, the initial concentration of $ A _{3} $ is "a" and $ molL^-1$ If x is degree of dissociation of $ A _{3} $. The total number of moles at equilibrium will be:- 

chemistry chemical equilibrium equilibrium in chemical processes introduction to equilibrium chemical equilibrium and acids-bases

  1. $a-\frac{ax}{3}$

  2. $\frac{2ax}{3}-3$

  3. $\frac{a-ax}{2}$

  4. None of these

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Correct Option: B

In which compound enol form is maximum

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. $CH _3-\overset{\overset{O}{||}}C-CH _3$

  2. ${ CH } _{ 3 }-CH=O$

  3. ${ CH } _{ 3 }-\underset { || }{ C } -{ CH } _{ 2 }-CH _3\ \quad \quad \quad  O$

  4. ${ CH } _{ 3 }-{ CH _2 } -{ CH } _{ 3 }\ \quad \quad \quad \quad $

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Correct Option: C

2 mole of ${ H } _{ 3 }{ PO } _{ 4 }$ has:

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. Two $\pi $-bond

  2. Seven mole of $\sigma $-bond

  3. Sixteen lone pair of electron

  4. Fourteen mole of $\sigma $-bond

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Correct Option: D

Geometry as sulphur is bent in 
I.${S} _{8}$ II.$S{F} _{2}$  III.$S{O} _{2}$

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. I, II, III

  2. I, II

  3. II, III

  4. I, III

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Correct Option: C
Explanation:

i. $S _8$ has rhombic shape.

ii.$SF _2$ has two lone pair and two particles geometry of $SF _2$ is bent or angular.
iii. $SO _2$ has one lone pair and $2$ oxygen molecules which gives bent geometry.

The enthalpy of reaction,${\text{2HC}} \equiv {\text{CH + 5C}}{{\text{O}} _{\text{2}}}{\text{ + 2}}{{\text{H}} _{\text{2}}}{\text{O}}\,$
 If the bounds energies of ${\text{C - H,C}} \equiv {\text{C,}}\,{\text{O = O,C = O}}$ abd ${\text{O - H}}$ bounds are p,q,r,s,t respectively 

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. $\left[ {8s + 4t} \right] - \left[ {4p + q + 5r} \right]$

  2. $\left[ {4p + 2q + 5r} \right] - \left[ {8s + 4t} \right]$

  3. $\left[ {4p + 2q + 5r + 8s + 4t} \right]$

  4. $\left[ {2q + q + 5r + } \right] - \left[ {8s + 4t} \right]$

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Correct Option: A

Decreasing order of bond length of marked carbon oxygen bounds 

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. $\alpha > \beta >\gamma $

  2. $\beta >\gamma > \alpha $

  3. $\beta >\alpha >\gamma $

  4. $\gamma > \beta > \alpha $

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Correct Option: D

The number of $\displaystyle \sigma-bond$ and $\displaystyle \pi- bond$ in $HCN$ are respectively:

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. $2$ and $2$

  2. $1$ and $3$

  3. $2$ and $1$

  4. None of these

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Correct Option: A
Explanation:

$H-C\equiv N$ contains $2$ sigma bonds and $2$ pi bonds.

Which of the following is not correct?

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. A sigma bond is weaker than pi bond.

  2. A sigma bond is stronger than pi bond.

  3. A double bond is stronger than a single bond.

  4. A double bond between two atoms is shorter than a single bond between the same atoms.

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Correct Option: A
Explanation:

A sigma bond is stronger than a $\pi$ bond due to axial overlapping of the orbitals.

A double bond is stronger than a single bond since now more energy is required to break two bonds.
Double bonds are $sp^2$ hybridized and are shorter in length.
Hence, the correct option is A.

Assertion: $\sigma$  is strong while $\pi$  is a weak bond.


Reason : Atoms rotate freely about  $\pi$  bond.

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. Both assertion and reason are true, and reason is not the true
    explanation of the assertion.

  2. Both assertion and reason are true, but reason is the true
    explanation of the assertion.

  3. Assertion is true, but reason is false

  4. Both assertion and reason are false.

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Correct Option: C
Explanation:

$\sigma$ bond is stronger than $\pi$ bond because in $\sigma$ bond the overlap is axial while in $\pi$ bond. It is lateral.


Due to the lateral overlap in $\pi$ bond atoms cannot rotate freely in $\pi$ bond.
So, assertion is true and reason is false.